Capsules are widely used in the pharmaceutical field as oral dosage form containers for administration to humans and animals of, e.g., pharmaceuticals, veterinary products, foods, and dietary supplements. Advantages of capsules over other dosage forms may include better patient compliance, greater flexibility in dosage form design, and less expensive manufacturing processes. Pharmaceutical capsules are conventionally divided into soft shell capsules (hereinafter softgel capsules) and hard shell capsules (hereinafter hard capsules). The characteristics of softgel and hard capsules are well known in the pharmaceutical field.
Hard capsule shells are generally manufactured using dip molding processes involving the use of pins dipped into solutions of the different ingredients that are needed for the making of the capsule shell containers. Methods for the manufacturing of soft gelatin or softgel capsule shells are also known in the art and are different from hard capsule shell manufacturing. Manufacturing of soft gelatin or softgel capsule shells at a production scale was introduced by Robert Pauli Scherer in 1933 with the invention of a rotary die encapsulation machine. The rotary die process involves continuous formation of a heat seal between two ribbons of gelatin simultaneous with dosing of the fill liquid into each capsule. Although manufacturing process speed and efficiency has improved with time, the basic manufacturing principle remains essentially unchanged. Before the encapsulation process takes place, two sub-processes are often carried out simultaneously, yielding the two components of a softgel capsule: (a) the gel mass which will provide the softgel capsule shell, and (b) the fill matrix for the softgel capsule contents. Softgel capsules have a continuous gelatin shell surrounding a liquid core, and are formed, filled, and sealed in one operation.
Softgel capsule walls are typically thicker than two-piece hard gelatin capsules, and their walls comprise plasticizers such as, for example, glycerol, sorbitol and/or propylene glycol to make the shell elastic. Processes for making softgel capsule shells are known, and softgel capsules are available commercially. See, e.g., Aulton, M., Aulton's Pharmaceutics: The Design & Manufacture of Medicines, 527-533 (Kevin M G Taylor, Ed., 3rd Ed., 2001). Softgel capsules have various advantages; they may show improved drug absorption, be easier to swallow, avoid dust handling issues, and have increased stability compared to other dosage forms. Softgel capsules may be filled with liquid fill such as oils and/or lipid soluble active ingredients such as pharmaceuticals, veterinary products, foods and dietary supplements.
Typical materials for both hard capsules and softgels include gelatin (of various sources including bovine, porcine, poultry, and/or fish) or non-gelatin materials such as synthetic polymers and/or plant-derived hydrocolloids. Gelatin is favorably used as shell forming material, particularly of softgels, due to its unique physiochemical properties, namely its oxygen impermeability and the combination of film-forming capability and thermoreversible sol/gel formation, that favor its use for the industrial capsule production, especially the softgel production via the rotary die process.
Softgel capsules may be desirable in view of their capability of storing liquid fills without requiring additional sealing procedures, as well as in some instances provide stability advantages when utilizing certain fills in view of the higher plasticizer content. The plasticizer content in softgels may further bring resistance to brittleness.
It may be desirable to provide stable dosage forms, made of a gelatin comprising material, and comprising active materials that would normally react with gelatin to provide instability and a change in the disintegration profile of the dosage form.
Typically, when faced with such stability issues, standard practice has been to focus the efforts on identifying suitable substitutes to gelatin, such as plant derived hydrocolloids (like in WO0137817) or synthetic polymers (like in WO9735537).
However, a need remains for achieving stable dosage forms using gelatin based materials.